AT Commands fail to Execute in a program

问题

The Program is shown below:

#include <SoftwareSerial.h>
SoftwareSerial gprsSerial(7, 8);

byte sensorInterrupt = 0;  // 0 = digital pin 2
byte sensorPin       = 2;

// The hall-effect flow sensor outputs approximately 4.5 pulses per second per
// litre/minute of flow.
float calibrationFactor = 4.5;

volatile byte pulseCount;

float flowRate;
unsigned int flowMilliLitres;
unsigned long totalMilliLitres;

unsigned long oldTime;

void setup()
{
  gprsSerial.begin(19200);
  Serial.begin(19200);

  pinMode(sensorPin, INPUT);
  digitalWrite(sensorPin, HIGH);

  pulseCount        = 0;
  flowRate          = 0.0;
  flowMilliLitres   = 0;
  totalMilliLitres  = 0;
  oldTime           = 0;

  // The Hall-effect sensor is connected to pin 2 which uses interrupt 0.
  // Configured to trigger on a FALLING state change (transition from HIGH
  // state to LOW state)
  attachInterrupt(sensorInterrupt, pulseCounter, FALLING);

  Serial.println("Config SIM900...");
  delay(2000);
  Serial.println("Done!...");
  gprsSerial.flush();
  Serial.flush();

  // attach or detach from GPRS service
  gprsSerial.println("AT+CGATT?");
  delay(100);
  toSerial();


  // bearer settings
  gprsSerial.println("AT+SAPBR=3,1,\"CONTYPE\",\"GPRS\"");
  delay(2000);
  toSerial();

  // bearer settings
  gprsSerial.println("AT+SAPBR=3,1,\"APN\",\"uninor\"");
  delay(3000);
  toSerial();


  // bearer settings
  gprsSerial.println("AT+SAPBR=1,1");
  delay(2000);
  toSerial();

  // bearer settings
  gprsSerial.println("AT+SAPBR=2,1");
  delay(3000);
  toSerial();


  gprsSerial.println("AT+HTTPINIT");
  delay(2000);
  toSerial();

}


void loop()
{
  if ((millis() - oldTime) > 1000)   // Only process counters once per second
  {
    // Disable the interrupt while calculating flow rate and sending the value to
    // the host
    detachInterrupt(sensorInterrupt);

    // Because this loop may not complete in exactly 1 second intervals we calculate
    // the number of milliseconds that have passed since the last execution and use
    // that to scale the output. We also apply the calibrationFactor to scale the output
    // based on the number of pulses per second per units of measure (litres/minute in
    // this case) coming from the sensor.
    flowRate = ((1000.0 / (millis() - oldTime)) * pulseCount) / calibrationFactor;

    // Note the time this processing pass was executed. Note that because we've
    // disabled interrupts the millis() function won't actually be incrementing right
    // at this point, but it will still return the value it was set to just before
    // interrupts went away.
    oldTime = millis();

    // Divide the flow rate in litres/minute by 60 to determine how many litres have
    // passed through the sensor in this 1 second interval, then multiply by 1000 to
    // convert to millilitres.
    flowMilliLitres = (flowRate / 60) * 1000;

    // Add the millilitres passed in this second to the cumulative total
    totalMilliLitres += flowMilliLitres;

    unsigned int frac;

    // Print the flow rate for this second in litres / minute
    Serial.print("Flow rate: ");
    Serial.print(int(flowRate));  // Print the integer part of the variable
    Serial.print("L/min");
    Serial.print("\t");       // Print tab space

    // Print the cumulative total of litres flowed since starting
    Serial.print("Output Liquid Quantity: ");
    Serial.print(totalMilliLitres);
    Serial.println("mL");
    Serial.print("\t");       // Print tab space
    Serial.print(totalMilliLitres / 1000);
    Serial.print("L");


    // Reset the pulse counter so we can start incrementing again
    pulseCount = 0;

    // Enable the interrupt again now that we've finished sending output
    attachInterrupt(sensorInterrupt, pulseCounter, FALLING);
  }


  // set http param value
  gprsSerial.println("AT+HTTPPARA=\"URL\",\"http://210.16.100.71:8090/watersupply/webservices/test.php?flowratereading=1500\"");
  delay(2000);
  toSerial();

  // set http action type 0 = GET, 1 = POST, 2 = HEAD
  gprsSerial.println("AT+HTTPACTION=0");
  delay(6000);
  toSerial();

  // read server response
  gprsSerial.println("AT+HTTPREAD");
  delay(1000);
  toSerial();

  gprsSerial.println("");
  delay(10000);
}

void toSerial()
{
  while (gprsSerial.available() != 0)
  {
    Serial.write(gprsSerial.read());
  }
}
void pulseCounter()
{
  // Increment the pulse counter
  pulseCount++;
}

AT Commands in the above program are not executing at once and showing Error: The result on the Serial monitor is shown below:

These Commands Executed Separately works like Charm.

回答1:

The main issue here is that nothing will ever work reliably or at all when you call delay instead of reading and parsing the responses given back from the modem. You MUST read and parse the responses given back.

Attempting to use delay is as useful as kicking dogs that stand in your way in order to get them to move. Yes it might actually work some times, but at some point you will be sorry for taking that approach...

For some guidelines of how to do this properly see this answer. I suspect that you possibly are aborting some of the commands, see the first part of this answer for some more details regarding that.

Side note: You should always disable interrupts for a period as short as possible, so you should definitely move all those Serial.print to after attachInterrupt.

来源：https://stackoverflow.com/questions/43247122/at-commands-fail-to-execute-in-a-program